Each year in the valve castings production, often due to pouring temperature scrap cast about 20% of the casting casting temperature and casting surface quality is closely related, therefore, to improve the valve castings yield, you need to control the pouring temperature.

1, the highest pouring temperature. Pouring temperature is too high will cause sand up, especially with a complex sand core castings, when the pouring temperature ≥ 1420 ℃ when the waste increased, pouring temperature of 1460 ℃ when the waste up to 50%. Therefore, the casting casting temperature should be controlled at the highest 1420 ℃ below.

2, the lowest pouring temperature. When the pouring temperature is lower than 1380 ℃, after processing the cast iron under the skin will find a single hole, the hole diameter is generally 1 ~ 3mm. In some cases there are only 1-2 holes, and these holes will appear with a small amount of liquid slag. Studies have shown that this defect is related to the pouring temperature, and when the pouring temperature is higher than 1380 ° C, this defect does not occur in the valve castings.

In summary, it can be seen that casting casting temperature should be controlled at 1380 ~ 1420 ℃. In addition, the pouring temperature is too low the most common reason is before pouring, molten iron in the open ladle for a long time to transport and stay and heat. With a ladle cover with a thermal insulation material, the heat loss can be significantly reduced.